Embattled Prime Minister Theresa May warned on Thursday that Britain will embark on a "path of deep and grave uncertainty" if it abandons a hard-won deal for leaving the European Union.

May insisted that the draft Brexit deal she has agreed with the EU will honour the votes of people who opted to leave the European Union by a 52% majority in a 2016 referendum.

The public "just want us to get on with it," she told reporters at Downing Street.

May insisted the draft deal would protect jobs, trade, security co-operation, the Northern Ireland peace process and an open Irish border.

Securing the deal has involved taking "difficult and uncomfortable decisions," she said, after facing widespread opposition to the draft deal from lawmakers in parliament earlier yesterday.

May was speaking amid calls from leading eurosceptics in her Conservative Party for no-confidence vote over the draft deal.

She would be forced out of office if she lost a no-confidence vote.

She was rocked earlier yesterday by the resignations of two cabinet ministers, including her Brexit Secretary Dominic Raab, in opposition to the draft agreement.

Jacob Rees-Mogg, who chairs the European Research Group of pro-Brexit Conservatives, sent a letter to the party's influential 1922 Committee, which must trigger a leadership contest if at least 15% of its 315 lawmakers request one.

Rees-Mogg wrote that May's proposed backstop for the Irish border, with separate provision for Northern Ireland from the rest of the United Kingdom, "stands in contradiction to our long-held principles."

The BBC reported that the 1922 Committee had not received the 48 letters required to trigger a vote.

May defended her draft deal in parliament but she faced criticism from all sides, with Mark Francois, the deputy chair of Rees-Mogg's group, warning that it was "impossible" to win a vote in parliament on the agreement.